Perdonally I don’t mind some relatively low fps while taxiing, landing or taking off as far as there’s no stutters and input lag. But usually it’s RAM and CPU instead of VRAM that is responsible for the last. With my 32 GB of RAM I see no slideshow even on the low fps.
35 or 20 fps would be a problem in a shooter or rising game but not a flight simulator for most of the people who just want an airliner experience. After all I am not there to do some Reno style races across the terminal buildings.
Movies are even at 24 fps and I don’t see people running out of cinema